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Mosquito behavior is heavily influenced by the chemical molecules in the environment. This knowledge can be used to modify insect behaviors; particularly to reduce vector-host contact as a powerful method for disease prevention. N,N-Diethyl-meta-toluamide (DEET) is the most widely used insect repellent in the market and an excellent example of a chemical that has been used to modify insect behavior for disease prevention. However, genetic insensitivity and habituation in Aedes aegypti (L.) mosquitoes after preexposure to DEET have been reported. In this study, we investigated the effect of preexposure to DEET on the downstream blood-feeding behavior of Ae. aegypti mosquitoes and the duration of the effect. We exposed mosquitoes to four different DEET concentrations: 0.10, 0.12, 0.14, and 0.16% for 10 min then allowed the mosquitoes to blood-feed on an artificial blood-feeding system either immediately or after being held for 1, 3, 6, or 24 h following DEET exposure. We found that preexposing Ae. aegypti mosquitoes to 0.14 or 0.16% DEET lowered their blood engorgement level, but did not alter their landing and probing behavior when compared to the control test populations. The reduction in complete blood-feeding was observed at all time periods tested, but was only statistically significant at 3 and 6 h after the preexposure process. Because reduction in blood meal has been associated with increased refeeding, future studies analyzing the effect of this behavior using arbovirus-infected mosquitoes are needed to address the concern of potentially increased vectorial capacity.

No licensed vaccine or antiviral drug against dengue virus (DENV) is available; therefore, most of the effort to prevent this disease is focused on reducing vector-host interactions. One of the most widely accepted methods of blocking vector-human contact is to use insect repellents to interfere with mosquito host-seeking behavior. Some arboviruses can replicate in the nervous system of the vector, raising the concern that arboviral infection may alter the insect behavioral response toward chemical stimuli. Three different Aedes aegypti (L.) mosquito cohorts: DENV-1-injected, diluent-injected, and uninjected were subjected to behavioral tests using a high-throughput screening system with 2.5% DEET and 0.14% DEET on 1, 4, 7, 10, 14, and 17 d postinjection. All test cohorts exhibited significant contact irritant or escape responses when they were exposed to 2.5% or 0.14% DEET. However, we found no biologically relevant irritancy response change in DENV-1-infected Ae. aegypti mosquitoes when they were exposed to DEET. Further studies evaluating the effects of other arboviral infections on insect repellents activity are necessary in order to provide better recommendation on the prevention of vector-borne disease transmission.